2,3,3,3-Tetrafluoropropene (CF3CF═CH2, HFO-1234yf) contains no chlorine and thus is useful as an alternative compound for chlorofluorocarbons to be used for e.g. refrigerants.
As a process for producing HFO-1234yf, a process may, for example, be mentioned wherein 1,1-dichloro-2,2,3,3,3-pentafluoropropane (CF3CF2CHCl2, HCFC-225ca) is subjected to a dehydrofluorination reaction to obtain 1,1-dichloro-2,3,3,3-tetrafluoropropene (CF3CF═CCl2, CFO-1214ya), and then, CFO-1214ya is reacted with hydrogen and reduced to obtain HFO-1234yf.
As a method of reducing CFO-1214ya to obtain HFO-1234yf, the following method (i) may, for example, be mentioned.
(i) A method for obtaining HFO-12-34yf by reacting CFO-1214ya and hydrogen in the presence of a catalyst having palladium supported on alumina (Patent Document 1).
However, the catalyst used in the method (i) has a drawback such that while the durability is high, side reactions are substantial to form by-products which can hardly be separated by distillation, and the conversion ratio to HFO-1234yf is low.
On the other hand, as a method for carrying out a similar reduction reaction, the following method (ii) has been proposed.
(ii) a method of reacting RfCF═CX2 (wherein Rf is a C1-10 fluoroalkyl group, and X is chlorine, bromine or iodine) with hydrogen in the presence of a catalyst having palladium supported on active carbon, to obtain RfCF═CH2 (Patent Document 2).
However, the catalyst used in the method (ii) has low durability in many cases, whereby it is required to change the catalyst frequently.